US6151117A - Optical sensor with telecentric optics - Google Patents
Optical sensor with telecentric optics Download PDFInfo
- Publication number
- US6151117A US6151117A US09/385,738 US38573899A US6151117A US 6151117 A US6151117 A US 6151117A US 38573899 A US38573899 A US 38573899A US 6151117 A US6151117 A US 6151117A
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- United States
- Prior art keywords
- substrate
- light
- sensing system
- sensor system
- image
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 230000003287 optical effect Effects 0.000 title description 11
- 239000000758 substrate Substances 0.000 claims abstract description 79
- 238000003384 imaging method Methods 0.000 claims description 4
- 108091008695 photoreceptors Proteins 0.000 description 9
- 239000000463 material Substances 0.000 description 4
- 238000000034 method Methods 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 229920002799 BoPET Polymers 0.000 description 1
- 239000005041 Mylar™ Substances 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
Images
Classifications
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/65—Apparatus which relate to the handling of copy material
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
- G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G2215/00—Apparatus for electrophotographic processes
- G03G2215/00362—Apparatus for electrophotographic processes relating to the copy medium handling
- G03G2215/00535—Stable handling of copy medium
- G03G2215/00717—Detection of physical properties
- G03G2215/00721—Detection of physical properties of sheet position
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G2215/00—Apparatus for electrophotographic processes
- G03G2215/00362—Apparatus for electrophotographic processes relating to the copy medium handling
- G03G2215/00535—Stable handling of copy medium
- G03G2215/00717—Detection of physical properties
- G03G2215/00759—Detection of physical properties of sheet image, e.g. presence, type
Definitions
- This invention relates to substrate and/or image sensors.
- Electrophotographic marking is a well-known and commonly used method of copying or printing original documents. Electrophotographic marking is performed by exposing a light image representation of a desired document onto a substantially uniformly charged photoreceptor. In response to that light image the photoreceptor discharges, creating an electrostatic latent image of the desired document on the photoreceptor's surface. Toner particles are then deposited onto the latent image to form a toner image. That toner image is then transferred from the photoreceptor onto a receiving substrate such as a sheet of paper. The transferred toner image is then fused to the receiving substrate. The surface of the photoreceptor is then cleaned of residual developing material and recharged in preparation for the production of another image.
- Most electrophotographic marking machines automatically fed various substrates, typically paper documents, through the machine. For example, blank sheets of paper or documents to be copied are automatically fed through the machine. To assist the marking process it is important that the positions of those moving substrates be tracked as they are fed.
- One way of tracking substrate positions is to use optical sensors.
- FIG. 1 shows a schematic diagram of a typical prior art substrate sensor system 12.
- a light emitting diode (LED) 54 emits light at a particular location.
- a phototransistor 56 is positioned to receive light from the LED 54 when a substrate is not between the LED 54 and the phototransistor 56.
- V 1 When light is received by the phototransistor 56 a relatively high electrical signal V 1 is applied to a Schmitt trigger 60.
- the Schmitt trigger 60 When light is not received by the phototransistor 56 a relatively low electrical signal is applied to the Schmitt trigger 60.
- the Schmitt trigger then outputs a signal V 0 with one state when a high electrical signal V 1 is present and the other state if a high electrical signal is not present.
- the signal V 0 thus signifies either the presence or the absence of a substrate 58 between the LED 54 and phototransistor 56. Additionally, since the signal V 0 makes a transition from one state to the other when either a leading edge or a trailing edge of the substrate 58 passes the sensing location, the state transition of V 0 signals the arrival or departure of a substrate at the sending position.
- the substrate sensor system 12 While the substrate sensor system 12 is generally successful, it has a limited sensitivity to document position. This is because the LED 54 emits light over a rather large area (thus is not a point source), because the phototransistor is sensitive to light over a relatively large area (thus is not a point sink), and because the document's position in the z-direction (the substrate 58 is in the x-y plane) is not well controlled. Therefore, when using the substrate sensor system 12 the absolute position of the leading and trailing edges are not accurately known. While position errors may only be tens of microns, in modern high quality electrophotographic printers such errors can be significant.
- One way of improving the substrate sensor system 12 would be to incorporate a simple imaging lens between the substrate and phototransistor, forming an image of the substrate onto an image plane located at the phototransistor.
- the phototransistor could also be replaced with an image sensor.
- This has the advantage that the magnification can be adjusted by selecting the lens focal length and the front and back conjugates. This is desirable since it may be advantageous to operate with a different size image on the sensor than is present in the paper path.
- the magnification varies. This magnification variation changes the size of the image, and hence the apparent position of the document's leading edge, just what is trying to be measured. Therefore, a substrate sensor system that is substantially tolerant of z direction variations would be beneficial.
- a substrate sensor system that is in accord with the principles of the present invention includes a light source for radiating light toward a substrate position, a light sensor system positioned to receive light transmitted or reflected from the substrate, a lens that images the light transmitted or reflected from the substrate onto the light sensor system, and a telecentric stop between the lens and the light sensor system.
- a substrate sensor system will also include an electrical circuit that produces position information regarding the position of a substrate and/or the position of an image on a substrate.
- FIG. 1 which illustrates a prior art substrate sensor system
- FIG. 2 which illustrates a substrate sensor system that is in accord with the principles of the present invention
- FIG. 3 which illustrates an alternative substrate sensor system that is also in accord with the principles of the present invention.
- FIG. 4 which illustrates a substrate having an image area.
- FIG. 2 illustrates a transmissive substrate sensor system 100 that is in accord with the principles of the present invention.
- a light emitting diode (LED) 154 emits light toward a linear photosensor array 156 that converts photons to electrons.
- An optical assembly 157 includes a lens 158 that images light transmitted past a substrate 162 onto the linear photosensor array.
- the optical assembly 157 further includes a telecentric stop 160. Reference, "The Telecentric Stop,” p. 131 of Modern Optical Engineering by Warren Smith, McGraw-Hill, New York, 1966. Electrical signals from the linear photosensor array 156 are applied to a position determining network 161.
- the components of the substrate sensor system are arranged such that the substrate 162 moving in a direction 164 can come between the LED 154 and the lens 158.
- the substrate which can be a document, or a photoreceptor belt, or other moving material, is nominally located in the object plane of the lens.
- the telecentric stop reduces the impact of z-direction variations in the position of the substrate.
- the position determining network 161 senses this light reduction and determines that the substrate is entering the sensing area. As the substrate continues to advance the light that reaches the individual photosensitive elements of the linear photosensor array 156 continues to drop. The position determining network 161 can thus accurately track the advancement of the substrate.
- FIG. 3 illustrates a reflective substrate sensor system 200 that is also in accord with the principles of the present invention.
- an LED 254 emits light toward a transparent platen 256 on which a document 258 is moving in a direction 260.
- Below the platen 256 is an optical assembly 264 having a lens 266 that gathers light reflected from the document 258.
- the optical assembly 264 further includes a telecentric stop 268.
- the optical assembly images light reflected by the document onto a linear photosensor array 270 that converts photons to electrons. Electrical signals from the linear photosensor array 270 are applied to an image determining network 272.
- the image determining network 272 senses this light increase and determines that the substrate is entering the sensing area. As the substrate continues to advance the light that reaches the individual photosensitive elements of the linear photosensor array 270 continues to increase. The image determining network 272 can thus accurately track the advancement of the substrate into and out of the sensing area. Significantly, the telecentric stop reduces the impact of z-direction variations in the position of the substrate.
- the principles of the present invention when sensing the position of images on a substrate.
- the substrate 258 has an image 300
- the light and dark areas of the image 300 will be imaged onto the linear photosensor array. These light and dark areas can be sensed by the image determining network to determine the position of the image on the document.
- the principles of the present invention are useful for locating images on a substrate.
- substrate requires particular attention.
- substrate seems to denote a sheet media of some type, such as paper or mylar.
- substrate is meant to denote any material suitable for carrying another material.
- substrate includes the photoreceptor. This is significant since one very useful application of the principles of the present invention is sensing registration ("fiducial") marks on a photoreceptor. By using the present invention to track such marks the position of the photoreceptor can be accurately known.
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Length Measuring Devices By Optical Means (AREA)
- Control Or Security For Electrophotography (AREA)
Abstract
Description
Claims (20)
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/385,738 US6151117A (en) | 1999-08-30 | 1999-08-30 | Optical sensor with telecentric optics |
JP2000250429A JP2001082922A (en) | 1999-08-30 | 2000-08-22 | Position detecting system |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/385,738 US6151117A (en) | 1999-08-30 | 1999-08-30 | Optical sensor with telecentric optics |
Publications (1)
Publication Number | Publication Date |
---|---|
US6151117A true US6151117A (en) | 2000-11-21 |
Family
ID=23522672
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/385,738 Expired - Fee Related US6151117A (en) | 1999-08-30 | 1999-08-30 | Optical sensor with telecentric optics |
Country Status (2)
Country | Link |
---|---|
US (1) | US6151117A (en) |
JP (1) | JP2001082922A (en) |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20020067483A1 (en) * | 2000-12-05 | 2002-06-06 | Philip Lacovara | Detection method and apparatus |
US20020134952A1 (en) * | 2001-02-02 | 2002-09-26 | Fuji Photo Film Co., Ltd. | Apparatus for detecting light-transmissive sheet-like body |
US6464417B2 (en) * | 1999-12-22 | 2002-10-15 | Hewlett-Packard Co. | Method and apparatus for print media detection |
WO2010133407A1 (en) * | 2009-05-22 | 2010-11-25 | Eastman Kodak Company | Method and device for the detection of a substrate edge in a printing machine |
US20110001067A1 (en) * | 2006-11-09 | 2011-01-06 | The Board Of Regents For Oklahoma State University | Fiber optic web edge sensor |
CN109506571A (en) * | 2018-10-26 | 2019-03-22 | 北京航天控制仪器研究所 | A kind of part dimension measurement method in place and device |
US11314190B2 (en) * | 2018-07-31 | 2022-04-26 | Hewlett-Packard Development Company, L.P. | Imaging system |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3782834A (en) * | 1971-05-17 | 1974-01-01 | Olympus Optical Co | Method of correcting photoelectric microscopes |
US5008743A (en) * | 1988-03-24 | 1991-04-16 | Orbot Systems Ltd. | Telecentric imaging system optical inspection machine using the same and method for correcting optical distortion produced thereby |
US5138178A (en) * | 1990-12-17 | 1992-08-11 | Xerox Corporation | Photoelectric paper basis weight sensor |
US5897611A (en) * | 1994-08-11 | 1999-04-27 | Cyberoptics Corporation | High precision semiconductor component alignment systems |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS59217108A (en) * | 1983-05-26 | 1984-12-07 | Konan Camera Kenkyusho:Kk | Detector of edge position |
JPH09105605A (en) * | 1995-10-12 | 1997-04-22 | Olympus Optical Co Ltd | Edge detection apparatus |
-
1999
- 1999-08-30 US US09/385,738 patent/US6151117A/en not_active Expired - Fee Related
-
2000
- 2000-08-22 JP JP2000250429A patent/JP2001082922A/en active Pending
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3782834A (en) * | 1971-05-17 | 1974-01-01 | Olympus Optical Co | Method of correcting photoelectric microscopes |
US5008743A (en) * | 1988-03-24 | 1991-04-16 | Orbot Systems Ltd. | Telecentric imaging system optical inspection machine using the same and method for correcting optical distortion produced thereby |
US5138178A (en) * | 1990-12-17 | 1992-08-11 | Xerox Corporation | Photoelectric paper basis weight sensor |
US5897611A (en) * | 1994-08-11 | 1999-04-27 | Cyberoptics Corporation | High precision semiconductor component alignment systems |
Non-Patent Citations (2)
Title |
---|
Article The Telecentric Stop, Example of Telecentric Optical System, Modern Optical Engineering by Warren Smith, p. 131. * |
Article--The Telecentric Stop, Example of Telecentric Optical System, Modern Optical Engineering by Warren Smith, p. 131. |
Cited By (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6464417B2 (en) * | 1999-12-22 | 2002-10-15 | Hewlett-Packard Co. | Method and apparatus for print media detection |
US6888635B2 (en) | 2000-12-05 | 2005-05-03 | Ambalux Corporation | Detection method and apparatus |
US20020067483A1 (en) * | 2000-12-05 | 2002-06-06 | Philip Lacovara | Detection method and apparatus |
US7145163B2 (en) | 2001-02-02 | 2006-12-05 | Fuji Photo Film Co., Ltd. | Apparatus for detecting light-transmissive sheet-like body |
US6943363B2 (en) * | 2001-02-02 | 2005-09-13 | Fuji Photo Film Co., Ltd. | Apparatus for detecting light-transmissive sheet-like body |
US20050269531A1 (en) * | 2001-02-02 | 2005-12-08 | Fuji Photo Film Co., Ltd. | Apparatus for detecting light-transmissive sheet-like body |
US20020134952A1 (en) * | 2001-02-02 | 2002-09-26 | Fuji Photo Film Co., Ltd. | Apparatus for detecting light-transmissive sheet-like body |
US20110001067A1 (en) * | 2006-11-09 | 2011-01-06 | The Board Of Regents For Oklahoma State University | Fiber optic web edge sensor |
US8324604B2 (en) * | 2006-11-09 | 2012-12-04 | The Board Of Regents For Oklahoma State University | Fiber optic web edge sensor |
WO2010133407A1 (en) * | 2009-05-22 | 2010-11-25 | Eastman Kodak Company | Method and device for the detection of a substrate edge in a printing machine |
US8760667B2 (en) | 2009-05-22 | 2014-06-24 | Eastman Kodak Company | Method and device for the detection of a substrate edge in a printing machine |
US11314190B2 (en) * | 2018-07-31 | 2022-04-26 | Hewlett-Packard Development Company, L.P. | Imaging system |
CN109506571A (en) * | 2018-10-26 | 2019-03-22 | 北京航天控制仪器研究所 | A kind of part dimension measurement method in place and device |
Also Published As
Publication number | Publication date |
---|---|
JP2001082922A (en) | 2001-03-30 |
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Legal Events
Date | Code | Title | Description |
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AS | Assignment |
Owner name: XEROX CORPORATION, CONNECTICUT Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:TUHRO, RICHARD H.;HERLOSKI, ROBERT P.;REEL/FRAME:010214/0670 Effective date: 19990826 |
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Owner name: BANK ONE, NA, AS ADMINISTRATIVE AGENT, ILLINOIS Free format text: SECURITY INTEREST;ASSIGNOR:XEROX CORPORATION;REEL/FRAME:013153/0001 Effective date: 20020621 |
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Owner name: JPMORGAN CHASE BANK, AS COLLATERAL AGENT, TEXAS Free format text: SECURITY AGREEMENT;ASSIGNOR:XEROX CORPORATION;REEL/FRAME:015134/0476 Effective date: 20030625 Owner name: JPMORGAN CHASE BANK, AS COLLATERAL AGENT,TEXAS Free format text: SECURITY AGREEMENT;ASSIGNOR:XEROX CORPORATION;REEL/FRAME:015134/0476 Effective date: 20030625 |
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Owner name: XEROX CORPORATION, NEW YORK Free format text: RELEASE BY SECURED PARTY;ASSIGNOR:JP MORGAN CHASE BANK, NA;REEL/FRAME:020031/0800 Effective date: 20061204 |
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Owner name: XEROX CORPORATION, NEW YORK Free format text: RELEASE BY SECURED PARTY;ASSIGNOR:BANK ONE, NA;REEL/FRAME:020045/0638 Effective date: 20030625 |
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STCH | Information on status: patent discontinuation |
Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362 |
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Effective date: 20121121 |
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Owner name: XEROX CORPORATION, CONNECTICUT Free format text: RELEASE BY SECURED PARTY;ASSIGNOR:JPMORGAN CHASE BANK, N.A. AS SUCCESSOR-IN-INTEREST ADMINISTRATIVE AGENT AND COLLATERAL AGENT TO JPMORGAN CHASE BANK;REEL/FRAME:066728/0193 Effective date: 20220822 |